Pre Exam # 2 Lecture

Question 1

Q # 2 It was stated that the patient, Robert had a wide range of auto-antibodies against various organ specific antigens as well as the liver and skin. How might a defect in normal T cell development lead to auto-antibody production?

Answer 1

No AIRE means no presentation of peptides by thymic medullary epithelial cells. single positive thymocytes cannot undergo negative selection, escape to the periphery, and are able to react with self peptides.

Question 2

What type of signal induces positive selection?

Answer 2

Weak signal

Question 3

What type of signal induces negative selection?

Answer 3

Strong Signal

Question 4

What type of signal produces Treg?

Answer 4

Intermediate signal, causes up regulation of FoxP3; Treg moves to the periphery and suppresses self reactive T cells.

Question 5

Experiments demonstrating negative selection showed that TCR transgenic mice specific for H-Y antigens were deleted in _________ mice

Answer 5

Male transgenic mice

Question 6

Name the three cell surface proteins expressed at the double positive stage?

Answer 6

CD4, CD8, a,b, CD3, complete TCR.

Question 7

Whats at the double negative stage?

Answer 7

CD44, CD25, Kit, pre TCR (rearranged beta chain, PreTalpha)

Question 8

Chaperone proteins that help stabilize class I in the ER include…

Answer 8

Calnexin, Calreticulin, ERP57, ERAP

Question 9

Tapasin

Answer 9

anchors MHC I w/TAP to each other.

Question 10

Peptide binding clefts in class II molecules differ from those in class I molecules in these 2 important ways

Answer 10

Class II has a larger peptide binding cleft (12-16, but upwards of 30+); Class II has four peptide binding clefts in the center; Class II has alpha and beta chain/ Class I has 8 -10 aa binding cleft, shorter, binds two anchor residues towards outside, made up of alpha and b2m chain.

Question 11

TCR resemble the ________ of antibody molecules

Answer 11

Fab

Question 12

This protein is required at the pre T cell stage to induce signaling

Answer 12

CD3 is the signaling portion

Question 13

Most of the variability found in the TCR is found in this region

Answer 13

in the peptide binding region; CDR3

Question 14

Name the two areas of the thymus that are important for positive and negative selection

Answer 14

positive selection occurs in the cortex; negative selection occurs in the medulla

Question 15

A mechanism by which exogenous proteins can be processed and presented to CD8 T cells is known as

Answer 15

Cross presentation (exception to rule # 1); done by DCs; exception to rule #2 autophagy.

Question 16

This cell type is responsible for positive selection

Answer 16

Thymic cortical epithelial cells.

Question 17

This type is responsible for negative selection

Answer 17

Bone derived DCs and macrophages

Question 18

If AIRE is expressed, this cell type plays a role in negative selection

Answer 18

Thymic medullary epithelial cells

Question 19

CD4 T cells express a surface protein that interacts with and binds to this

Answer 19

MHC II

Question 20

What does CD8 bind to?

Answer 20

MHC I

Question 21

At the pre T cell stage, the pre-TCR signals the cell to block ( 1 of four things pre-TCR does)

Answer 21

further b chain rearrangement; alleic exclusion

Question 22

Pre-TCR also signals to initiate (3 things)

Answer 22

alpha chain rearrangement, induces the expression of CD4/CD8, induces proliferation

Question 23

Class I molecules consists of an alpha chain and a

Answer 23

b2m chain (invariant)

Question 24

HLA-DM functions to help class II anitgen processing by

Answer 24

peptide editing, removing CLIP

Question 25

TCR contacts both the MHC molecule and

Answer 25

peptide

Question 26

Most T cell receptors are comprised of _________ and blank______

Answer 26

alpha and beta proteins/ 5% gamma delta

Question 27

Positive selection occurs at this stage of development and assures that the mature T cells are

Answer 27

cortex at the double positive stage; assures that the mature T cells are MHC restricted

Question 28

What is the process that makes thymocytes T cell tolerant

Answer 28

negative selection

Question 29

Deficiency in this ER residing protein leads to an absence of CD8 T cells

Answer 29

TAP1&2/MHC I deficiency; no CD8 T cells

Question 30

The pre TCR is expressed at this stage

Answer 30

double negative ( DN3-4)

Question 31

Class I molecules accommodate peptides of this length

Answer 31

8-10aa; class II 15-30

Question 32

This transcription factor is important to commit HSCs to the T Cell lineage

Answer 32

Notch-1

Question 33

Multiple alleles at each locus of the gene encoding the HLA in a population as a whole is known as

Answer 33

as polymorphism – for class II, most of the polymorphism occurs in the beta chain

Question 34

Polygenic vs polymorphism

Answer 34

How many different HLA molecules do your cells expressed – three class I and three class II (the polygenic is that there are three different class I and class II molecules)

Question 35

This transcription factor regulates expression of tissue specific antigens for tolerance induction

Answer 35

AIRE